AN EXACT FORMULATION FOR THE ELECTROMAGNETIC-FIELDS OF A CYLINDRICAL-ANTENNA WITH A TRIANGULAR CURRENT DISTRIBUTION

A mathematically exact formulation for the vector potential and corres ponding electromagnetic fields of a triangular current cylindrical dip ole are presented for the first time in this paper. These exact expres sions converge rapidly in the near-field region of the antenna allowin g them to be used for the efficient and accurate computational modelin g of electrically short cylindrical antennas. The exact series expansi on of the triangular current vector potential is shown to contain two fundamental exponential integrals and their higher-order associated in tegrals. Numerically stable forward recurrence relations have been der ived which may be used for the efficient evaluation of these higher-or der integrals in addition to the cylindrical wire kernel. These recurs ions may also be employed in the computation of the electric and magne tic fields. It is demonstrated that the classical thin wire forms of t he vector potential and electromagnetic fields are actually special ca ses of the more general exact expansions. Finally, the exact formulati on was used to investigate the near-field behavior of traditional thin wire as well as moderately thick wire dipoles. Several near-field plo ts are presented including a vector plot of the total electric field i n the vicinity of a moderately thick quarter-wavelength dipole.